Method of forming a molded silicone foam implant having open-celled interstices

Abstract

A breast prosthesis for implantation beneath the skin is disclosed. In one preferred embodiment the prosthesis has an outer elastic shell which encloses a biocompatible fluid and a silicone foam insert of unitary construction having the shape and approximate consistency of breast tissue. The foam insert occupies substantially the entire volume enclosed by the shell of the implantable prosthesis and consists of a foam body that is molded to the shape of the breast. The foam body has both open-cell and closed-cell characteristics. Portions of the foam insert are closed-cell with open-cell passageways threading themselves throughout the structure. The insert is of unitary construction and made by (a) heating a mold to an appropriate temperature; (b) mixing air bubbles into dispersion of uncured silicone; (c) injecting the bubble-laden, uncured silicone into the preheated mold; and (d) applying a vacuum until the foam insert cures. The volume of the foam insert should preferably be substantially equal to the unstretched volume of the shell which surrounds the foam body. In another preferred embodiment only a portion of the volume enclosed by the cell is occupied by the foam insert. In this embodiment, one surface of the foam insert conforms to the curvature of at least a portion of the shell and may be affixed to the conforming inner surface of the shell thereby effectively thickening or reinforcing the overlying shell. In yet another embodiment a foam insert made as described above comprising an open-cell and closed-cell foam body may directly implanted beneath the skin for breast augmentation or reconstruction without a shell. The inner surface of the mold may be textured to provide additional opportunity for desirable tissue ingrowth following implantation.

What I claim is: 
     
       1. A method for making a foam insert for use with a saline filled breast implant comprising the steps of: (a) creating gaseous bubbles within a fluid silicone;   (b) preheating a mold to 200° to 300° F.;   (c) injecting said fluid silicone containing said bubbles into a cavity within the preheated mold;   (d) reducing the external pressure exerted on said fluid silicone within said cavity of said mold below atmospheric pressure;   (e) curing said fluid silicone by holding the mold at elevated temperature and reduced pressure for 30 to 60 minutes to form a foam insert; and   (f) removing said foam insert from said cavity in said mold, wherein the reduced pressure operates to force a portion of said bubbles from said fluid silicone while said fluid silicone is curing to form said foam insert having open-celled interstices.